Critical Reviews in Food Science and Nutrition

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Brassica Foods as a Dietary Source of Vitamin C: A Review a

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R. Domínguez-Perles , P. Mena , C. García-Viguera & D. A. Moreno

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Phytochemistry Lab. Department of Food Science and Technology , Centro de Edafología y Biología Aplicada del Segura-Consejo Superior de Investigaciones Científicas (CEBAS-CSIC) , Espinardo , Murcia, 30100 , Spain Accepted author version posted online: 26 Mar 2013.Published online: 05 Feb 2014.

To cite this article: R. Domínguez-Perles , P. Mena , C. García-Viguera & D. A. Moreno (2014) Brassica Foods as a Dietary Source of Vitamin C: A Review, Critical Reviews in Food Science and Nutrition, 54:8, 1076-1091, DOI: 10.1080/10408398.2011.626873 To link to this article: http://dx.doi.org/10.1080/10408398.2011.626873

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Critical Reviews in Food Science and Nutrition, 54:1076–1091 (2014) C Taylor and Francis Group, LLC Copyright  ISSN: 1040-8398 / 1549-7852 online DOI: 10.1080/10408398.2011.626873

Brassica Foods as a Dietary Source of Vitamin C: A Review

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* ´ ´ R. DOMINGUEZ-PERLES, P. MENA,* C. GARCIA-VIGUERA, and D. A. MORENO

Phytochemistry Lab. Department of Food Science and Technology. Centro de Edafolog´ıa y Biolog´ıa Aplicada del Segura-Consejo Superior de Investigaciones Cient´ıficas (CEBAS-CSIC), Espinardo, Murcia 30100, Spain

Brassica genus includes known horticultural vegetables with major economical importance worldwide, and involves vegetables of economical importance being part of the diet and source of oils for industry in many countries. Brassicales own a broad array of health-promoting compounds, emphasized as healthy rich sources of vitamin C. The adequate management of pre- and postharvest factors including crop varieties, growth conditions, harvesting, handling, storage, and final consumer operations would lead to increase or preserve of the vitamin C content or reduced losses by interfering in the catalysis mechanisms that remains largely unknown, and should be reviewed. Likewise, the importance of the food matrix on the absorption and metabolism of vitamin C is closely related to the range of the health benefits attributed to its intake. However, less beneficial effects were derived when purified compounds were administered in comparison to the ingestion of horticultural products such as Brassicas, which entail a closely relation between this food matrix and the bioavailability of its content in vitamin C. This fact should be here also discussed. These vegetables of immature flowers or leaves are used as food stuffs all over the world and represent a considerable part of both western and non-Western diets, being inexpensive crops widely spread and reachable to all social levels, constituting an important source of dietary vitamin C, which may work synergistically with the wealth of bioactive compounds present in these foods. Keywords Vitamin C, Brassica, ascorbic acid, dehydroascorbic acid, pre-harvest, post-harvest, bioavailability, health

1. INTRODUCTION The Brassicaceae crop plants (broccoli, cauliflower, Brussels sprouts, cabbages, turnips, etc.) are food staples used worldwide (Figure 1) and represent a considerable portion of human diet (Vallejo et al., 2002b; Jahangir et al., 2009; Kusznierewicz et al., 2010). A broad array of healthy properties have been attributed to Brassica species in recent years; such as anticarcinogenic, protective actions against cardiovascular diseases and ageing processes, prenatal pathologies, cataracts, etc. (Kataya and Hamza, 2008; Kim et al., 2008; Tiku et al., 2008; Jahangir et al., 2009; Akhlaghi and Bandy, 2010; Emmert et al., 2010). These benefits have been related to their high content in

Address correspondence to D. A. Moreno, Phytochemistry Lab. Department of Food Science and Technology. Centro de Edafolog´ıa y Biolog´ıa Aplicada del Segura-Consejo Superior de Investigaciones Cient´ıficas (CEBASCSIC), Post Office Box 164, Espinardo, Murcia 30100, Spain. E-mail: [email protected] ∗ These two authors have contributed equally to the present work.

health-promoting phytochemicals namely: glucosinolates (and their hydrolysis products, isothiocianates), phenolic compounds (hydroxycinamic acids and flavonoids), carotenoids, vitamins (ascorbic acid (AA), tocopherol, and folic acid), and minerals (Vallejo et al., 2002a; Heimler et al., 2006; Fernandes et al., 2007; Ferreres et al., 2009; Taveira et al., 2009; Dom´ınguezPerles et al., 2010; Yang et al., 2010; P´erez-Balibrea et al., 2011). Regardless of the rich profile in bioactive compounds of Brassica genus, current trials are focused on the potential role of isolated phytochemicals, including vitamin C, largely known as essential nutrient, that lacks an integrative approach to understand its functions on health along with the rest of bioactive constituents in their natural food concentrations and the conditioning of the food matrix on its bioavailability (Blot et al., 1993; Loria et al., 2000; Bjelakovic et al., 2007; Li and Schellhorn, 2007a; Frei and Lawson, 2008; Kim et al., 2008). Actually, it should be taken into account that Brassicas generally contain high amounts of vitamin C, even though the traditional source has also been the Citrus family. In fact, depending on consumer habits of different countries, Brassica vegetables can provide the 50% of the daily recommended dietary intake of vitamin C,

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Figure 1

Vernacular and scientific names of some examples of commercial Brassicaceae.

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leading the sources of natural vitamin C for human populations (Pennington and Fisher, 2010). Therefore, the aim of this review was to describe the existing variations in the contents of vitamin C among Brassica species, pointing out the effects of the preharvest (specie, variety, organ, and developmental stage) and postharvest (handling, storage, and processing procedures) on this nutrient for high quality commodities. The relevance of the health benefits attributed to vitamin C derived from the Brassica consumption as affected by the food matrix, as well as its absorption and metabolism, will also be discussed. 2. PREHARVEST CONDITIONS AFFECTING VITAMIN C CONTENT IN BRASSICA FOODS The capital relevance of preharvest factors on the nutritional quality of Brassica foods has been widely reported and it is clear that the adequate management of the production factors affecting the plant growth may help to increase their content in bioactive compounds at harvest, not only by selecting the best species and varieties for any specific production area, but also by optimizing the growing conditions of the selected crops. Therefore, among the different preharvest factors conditioning the vitamin C content of Brassica vegetables, two groups could be established. First, those factors inherent to the considered crop: genetic (species and cultivars) and physiological factors (organ and developmental stage), as “internal” factors. In this sense, the second group would include all the “external” factors including the environmental and agronomic conditions and practices harvesting and handling procedures. 2.1. Genetic Information The major inherent internal factor to crucifers is the large variation among genotypes, and a good example can be founding Brassica genus (Table 1), for vitamin C concentrations ranging up to fourfold differences among species: broccoli (B. oleracea var. italica), Brussels sprouts (B. oleracea var. gemmifera), kale (B. oleracea var. acephala), and mustard spinachs (B. rapa var. perviridis), exhibing higher contents (100, 107, 118, and 130 mg of vitamin C per 100 g fw on average, respectively), widely surpassed the black mustards (B. nigra), canola (B. napus), cauliflower (B. oleracea var. botrytis), collards (B. oleracea var. viridis), Indian mustards (B. juncea var. rugosa), turnips (B. rapa vars. rapifera and rapa), and cabbages (B. oleracea var. capitata, B. rapa var. chinensis, var. parachinensis, and var. pekinensis) that presented ranging 35–68 mg 100 g−1 fw (Table 1). Data of the variation of vitamin C contents of different Brassica species analyzed under equal conditions have been published by the United States Department of Agriculture (USDA), confirming this fact under the minimized influence of the analytical method (USDA, 2010). Penintong et al. cited an alternative classification that showed collards, kale, turnip greens, and mustards as the Brassicas with

the highest contents in vitamin C in comparison with broccoli, Brussels sprouts, cabbage, cauliflower, Chinese broccolis, and Chinese cabbages (Pennington and Fisher, 2010). In earlier works, the lowest values have been registered for some varieties of cabbage (5.7–25.3 mg 100 g−1 fw (Singh et al., 2007)). Additionally, the comparison of the content of vitamin C in separate cultivars belonging to the same species has shown differences of up to 5% for broccoli, 3.7% for kale, 2.7% for collards, 2% for cauliflower, Indian mustards, cabbage, and turnips, and 1.5% for Brussels sprouts and Chinese cabbage (Table 1). The variation in the content of vitamin C among Brassicaceae members has been attributed to their inherent genetic background, while minor changes could be also attributed to differences in the experimental procedures or analytical methods. In addition, the fact that the species most widely integrated in the market and human consumption habits (broccoli, kale, collards, and cauliflower), and therefore, which are subjected to more intense genetic breeding showed also the strongest variation, linking the genetic factor as responsible of the variation in their vitamin C contents. Furthermore, the experimental procedures in which variations in the analytical and storage conditions, represent a factor with marginal relevance, give additional support to the critical effect of the genetic influence on the vitamin C content in Brassica spp., with variations of up to 54% for broccoli, 12% for cauliflower, and 32% for cabbage (Kurilich et al., 1999; Ferreres et al., 2006; Vrchovsk´a et al., 2006; Borowski et al., 2008; Sousa et al., 2008). In this sense, Vallejo et al., analyzed the content in vitamin C of 14 breeding and commercial broccoli varieties recording differences of up to 71% (Vallejo et al., 2002b), even though they were grown, processed, and analyzed under equal conditions, suggesting again the major relevance of the genetics and breeding in determining the Brassicas load of dietary vitamin C over the distinct experimental conditions. Despite the existing variations in vitamin C contents in Brassicas, we emphasize that the natural foods of this genus are a good source of vitamin C among a broad array of fruits and vegetables.

2.2. Organ and Developmental Stage Other group of inner factors; including the physiological effects of the distinct plant organs, or the developmental stage at harvest, are also critical for the nutrient contents of fruits and vegetables. Considering broccoli as a model because of its intense characterization and interest as commercial Brassica, significant changes occurred on vitamin C levels through its development, as for other bioactives. While in broccoli seeds, vitamin C is almost undetected, a progressive increase of the vitamin C in broccoli sprouts was described from 3 to 12 days of age (P´erez-Balibrea et al., 2008; P´erez-Balibrea et al., 2010). Later on, in adult plants during flowering, the vitamin C accumulation in broccoli inflorescences from the early flower bottom to the mature head reached even a fivefold increased amount (Omary et al., 2003; Vallejo et al., 2003a). Another remarkable

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BRASSICA FOODS AS A DIETARY SOURCE OF VITAMIN C

Table 1

Content in vitamin C (mg 100 g−1 fw) of fresh edible parts of Brassica plants

Commodity

AA

Broccoli (Brassica oleracea var. italica)

106.9

Vitamin C 93.2 83.0 66.4 72.2–122.6 37.7–124.9 ∼200 ∼115 (leaves) ∼150 117.7 130 25.5–82.3

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77–93

Extraction/analysis method Total ascorbic acid Trichloroacetic acid/HPLC Till-mans method MeOH:H2O/HPLC

MeOH:H2O/HPLC Nonavailable Citric acid/HPLC Methaphosphoric acid/2,6-Dichloroindophenol

74.8 96.79 32

112 (78 stems) 89.0–148.2

2.34–5.77∗

97.0–163 121.1

Metaphosphoric acid/microfluorometric method Metaphosphoric acid/spectophotometry Methaphosphoric acid/HPLC

74.7 ∼152 75 43.2–146.3 103 (124 stems) 41–64 87.19 374.1 113 93

Not available

20.1 26.6 85

Total ascorbic acid MeOH:H2O/HPLC Total ascorbic acid

90.3

Till-mans method Methaphosphoric acid/HPLC

35–65 Broccoli raab (Brassica rapa var. ruvo) Brussels sprouts (Brassica oleracea var. gemmifera) 27.4 76

Cauliflower (Brassica oleracea var. botrytis)€

127.7–129.3 87–109 48.2

63.1

No available Total ascorbic acid Trichloroacetic acid/HPLC Till-mans method Metaphosphoric acid/2,6-dichlorophenol HCl/2,6-dichlorophenol Citric acid/HPLC-UV Methaphosphoric acid/HPLC

64–78 28.2

No available Total ascorbic acid

45.0 25.3

Total ascorbic acid Metaphosphoric acid/2,6-dichlorophenol-indophenol Methaphosphoric acid/HPLC Total ascorbic acid Citric acid/HPLC-UV Methaphosphoric acid/HPLC

81 40.6–52.4 50 17.2 64 54.0 42.0

Chinese broccoli (Kai lan) (Brassica alboglabra) Chinese cabbage (Pak choi) (Brassica rapa var. chinesis)

Chinese cabbage (Pe tsai) (Brassica rapa var. pekinensis)

29 27.0 11 20

Source (Reference) (USDA, 2010) (Puupponen-Pimi¨a et al., 2003) (Sikora et al., 2008) (Vallejo et al., 2003b) (Vallejo et al., 2003a) (L´opez-Berenguer et al., 2007) (L´opez-Berenguer et al., 2009) (L´opez-Berenguer et al., 2009) (Vallejo et al., 2002a) (Moreno et al., 2007a) (Jagdish et al., 2006) (Hrncirik et al., 2001) (Favell, 1998) (Bahorun et al., 2004) (Schonhof et al., 2007) (Ansorena et al., 2011) (Borowski et al., 2008) (Murcia et al., 2000) (Vanderslice et al., 1990) (Mangels et al., 1993) (Kurilich et al., 1999) (Howard et al., 1999) (Hussein et al., 2000) (Vallejo et al., 2002b) (Zhang and Hamauzu, 2004) (Franke et al., 2004) (Koh et al., 2009) (Patras et al., 2011) (Davey et al., 2000) (Chu et al., 2002) (Lemoine et al., 2010) (USDA, 2010) (Cefola et al.) (USDA, 2010) (Sikora et al., 2008) (Kurilich et al., 1999) (Pfendt et al., 2003) (Podsedek et al., 2006) (Davey et al., 2000) (USDA, 2010) (Puupponen-Pimi¨a et al., 2003) (Sikora et al., 2008) (Bahorun et al., 2004) (Pfendt et al., 2003) (Hrncirik et al., 2001) (Vanderslice et al., 1990) (Kurilich et al., 1999) (Davey et al., 2000) (USDA, 2010) (USDA, 2010) (Bahorun et al., 2004) (Wills et al., 1984) (USDA, 2010) (Hrncirik et al., 2001) (Wills et al., 1984) (Continued on next page)

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Content in vitamin C (mg 100 g−1 fw) of fresh edible parts of Brassica plants (Continued)

Commodity Chinese flowering cabbage (Choi sum) (Brassica rapa var. parachinensis) Collards (Brassica oleracea var. viridis) Curly kale (Brassica oleracea var. acephala)

AA

92.7

Vitamin C

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Mustard cabbage (Indian mustard) (Brassica juncea var. juncea)

36.2

Mustard spinach (Tender greens) (Brassica rapa var. perviridis) Red cabbage (Brassica oleracea var. capitata) Savoy cabbage (Brassica oleracea var. capitata) White cabbage (Brassica oleracea var. capitata)

5.5 44 28.2 18.8

42.3–67.0 17.0–24.0

White or yellow mustard (Brassica alba) Turnip tops (Brassica rapa var. Rapiferaa) Turnip greens (Brassica rapa var. Rapa)

Source (Reference)

46

Methaphosphoric acid/HPLC

(Wills et al., 1984)

35.3 93.3 120 107 51.3

Total ascorbic acid Methaphosphoric acid/HPLC Total ascorbic acid Till-mans method Methaphosphoric acid/dinitrophenylhydrazine method HCl/2,6-dichlorophenol-indophenol Methaphosphoric acid/HPLC-UV

(USDA, 2010) (Vanderslice et al., 1990) (USDA, 2010) (Sikora et al., 2008) (Fonseca et al., 2005)

92.6 730∗

Extraction/analysis method

55.52 969∗ 186 70.0 36.2 100 130.0 57.0 62.0–72.5 31.0 49.8–65.7 33.3 36.6 25.6

Not available Total ascorbic acid Methaphosphoric acid/HPLC Total ascorbic acid Total ascorbic acid Methaphosphoric acid/HPLC-UV Total ascorbic acid Methaphosphoric acid/HPLC-UV

18.0–35.6 44.3–74

Total ascorbic acid Manufactured kit/HPLC Citric acid/HPLC-UV HCl/2,6-dichlorophenol Metaphosphoric acid/2,6-dichlorophenol-indophenol Methaphosphoric acid/HPLC Not available

46–47 32 43 34.1 3

Total ascorbic acid

21.0 46 89.39 60.0 62 67.5 ∼70

Total ascorbic acid MeOH:H2O/HPLC Methaphosphoric acid/HPLC MeOH:H2O/HPLC Methaphosphoric acid/HPLC Not available

(Pfendt et al., 2003) (Mart´ınez et al., 2009) (Hagen et al., 2009) (Davey et al., 2000) (USDA, 2010) (Vanderslice et al., 1990) (Wills et al., 1984) (USDA, 2010) (USDA, 2010) (Podsedek et al., 2006) (USDA, 2010) (Podsedek et al., 2006) (Mart´ınez et al., 2009) (USDA, 2010) (G¨okmen et al., 2000) (Hrncirik et al., 2001) (Pfendt et al., 2003) (Bahorun et al., 2004) (Podsedek et al., 2006) (Vanderslice et al., 1990) (Kurilich et al., 1999) (Davey et al., 2000) (Chu et al., 2002) (Puupponen-Pimi¨a et al., 2003) (Mart´ınez et al., 2009) (USDA, 2010) (USDA, 2010) (Francisco et al., 2010) (Mart´ınez et al., 2009) (USDA, 2010) (Francisco et al., 2010) (Mart´ınez et al., 2009) (Mondrag´on-Portocarrero et al., 2006)

NDB = USDA nutrient databank identifier, ∗ mg g−1 dw; ∗∗ mg Kg−1 pf.

increase was observed in leaves and stalks in adult plants. Indeed, Brassica byproducts (harvest remains) are foodstuffs rich in health-promoting nutrients including vitamins and minerals, with even higher values that those found in marketable heads (Omary et al., 2003; Mart´ınez et al., 2009; Dom´ınguez-Perles et al., 2010). Consequently, the stage of plant development conditions the content of phytochemicals including vitamin C. 2.3. Environmental Factors Concerning “external” environmental and agronomic factors that influence the vitamin C contents of Brassica crops

(Howard et al., 1999), sun light, aerial temperature, and soil salinity have been highlighted as critical factors for vitamin C, and therefore modifiers of the nutritional quality of Brassicas (Lee and Kader, 2000; Moreno et al., 2007a; L´opez-Berenguer ˜ et al., 2009; DomAnguez-Perles et al., 2010). With regard to sunlight, although vitamin C synthesis in plants is not directly depending on light, AA is synthesized from glucose obtained through the photosynthesis, which let to an indirect relationship between both, amount and intensity of sunlight and the vitamin C content (Lee and Kader, 2000). In the same way, Perez-Balibrea et al. recorded higher contents of vitamin C in broccoli sprouts grown under a 16/8 h light/dark cycle, that

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BRASSICA FOODS AS A DIETARY SOURCE OF VITAMIN C

significantly surpassed those of the sprouts grown in the dark, by 83% on average (P´erez-Balibrea et al., 2008). Likewise, the relationship between air temperature and AA content has also been reported for Brassica vegetables and, in general, growing under low temperature regimes has as consequence a higher vitamin C contents in plants (Lee and Kader, 2000). Considering abiotic stress such as salinity in the irrigation water, its concentration is crucial for the vitamin C content of edible parts of Brassicas, including broccoli, decreasing proportionally to the water physiological deficiency or hydric stress (Toivonen et al., 1994). Several production areas of semiarid climates worldwide are affected by water shortage, and characterized by high-salt concentrations in the available irrigation water, which has been pointed out as responsible of the variations in the nutritional value of Brassica foods. However, the variation in vitamin C content, as a consequence of the irrigation using saline water, is closely related to the organ considered: while broccoli inflorescences and stalks were not affected, the broccoli leaves showed a decrease (15% as average) in vitamin C at 100 mM ˜ NaCl (L´opez-Berenguer et al., 2009; DomAnguez-Perles et al., 2010). Fertilization practices are also critical for growth and the nutritive composition of crops, and the effects on the vitamin C of Brassica plants depends on type of nutrient and the applied dose. The sulfur fertilization (60–200 Kg Ha−1) at low or too high rate at different flowering moments resulted in distinct vitamin C contents with a positive effect of rich sulfur fertilization, at the beginning of the inflorescence development, undergoing a progressive reduction in concentration during heads formation (Vallejo et al., 2003a, 2003b). For nitrogen, its application (100–400 Kg Ha−1) severally leads to higher vitamin C concentrations in vegetables (Stefanelli et al., 2010), and among Brassicas, cauliflower and white cabbage have displayed an increased vitamin C content when the nitrogen based fertilization was at low rates (Sorensen, 1984; Lisiewska and Kmiecik, 1996). However, it has not been registered significant differences for vitamin C content of broccoli, suggesting the relative effect of fertilization practices on its content, as well as the contribution of climate and water status together with the fertilization effects (Sorensen, 1984; Lisiewska et al., 2008; Stefanelli et al., 2010). The AA appeared to be strongly affected by a fast oxidation to DHA under nonadequate growth conditions for broccoli. Indeed, both seasonal and annual variations of the AA and total vitamin C have also been observed (between 13.37–110.30 and 57.35–131.35 mg/100 g fw, respectively), for example, in broccoli harvested in separated seasons for two consecutive years (Koh et al., 2009). Harvesting marks the limit between pre- and postharvest. Manipulations at harvest may cause damages on the integrity of Brassica tissues as a result of bruising, surface abrasions, and cuts. Consequently, harvesting methods may have pernicious effects on vitamin C content, accelerating its loss or degradation by exposing it to external oxidative atmospheres. Like this, the method employed for harvesting, either by hand or using machinery, can determine the severity of the damages caused to

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the marketable products. Therefore, harvesting procedures and practices should be the less damaging as possible to avoid vitamin C losses and keep the integrity of the item and its content and, in addition, must be stored at low temperatures (Lee and Kader, 2000; Sikora et al., 2008).

3. POSTHARVEST CONDITIONS AFFECTING VITAMIN C CONTENT IN BRASSICA PRODUCTS Post-harvest products would determine the potential amount of nutrients and health promoting bioactives for dietary intake by final consumers and, hence, their properties for consumers wellbeing. The food composition would be greatly influenced by the processes at this stage. Once harvested, the biological processes that continue in food, are closely linked to the variation of phytochemical composition during handling and storage. Because of this, preserving the phytochemicals in Brassica vegetables through careful post-harvest practices means to guarantee their high nutritional quality and safety (Allende et al., 2006). In this sense, vitamin C has been considered a bio-indicator of adequate handling and processing procedures because of its sensitivity to degradation (it is easily oxidized by both enzymatic and nonenzymatic pathways) (Morrison, 1974; Clegg et al., 1976) and, in general, fresh Brassica foods contain higher vitamin C contents than stored foods, not only as a result of the slight increase of vitamin C occurred in some species during first days after harvesting (Eheart and Odland, 1972; Wu et al., 1992), but also because it is not possible to stop the degradation processes after harvest. Vitamin C losses begin during pre-market preparations of Brassica vegetables, which may include bruising, trimming, and cutting, which can display an intense reduction as a result of these processes that entails a weak commercial and healthy value (Lee and Kader, 2000; Sikora et al., 2008). Moreover, there are a broad array of post-harvest factors affecting vitamin C content of Brassica vegetables such as storage temperature, packing atmospheres, edible coatings, and cooking methods. In fact, the combination of all these factors will notably affect the final vitamin C content of foods-as-eaten, as it has already been noted for some Brassica vegetables including Broccoli (Puupponen-Pimi¨a et al., 2003; Lemoine et al., 2007; L´opez-Berenguer et al., 2007), collards (Vanderslice et al., 1990), cabbage (Kader; Vanderslice et al., 1990; PuupponenPimi¨a et al., 2003), mustard greens (Vanderslice et al., 1990), and cauliflower (Puupponen-Pimi¨a et al., 2003). These reports have showed that the chain of factors from the producer to the consumer let to degradation of vitamin C to different extends for Brassicas. 3.1. Storage Temperature This factor is critical for the maintenance of the vitamin C level in Brassica spp. foods (Table 2). Refrigeration of Brassica derived foods is used to maintain the vitamin C concentration

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Table 2

Content in vitamin C (mg 100 g−1 fw) of stored and cooked edible parts of Brassica plants

Commodity

Frozen

Refrigerated

Broccoli 56.0 (frozen); 23.1 (boiled/frozen) 56.4 64.3–73.7 77–89 (frozen); 77–86 (blanched/frozen); 69–80 (microwaved/frozen)

Cooked (cooking method) 40.1

(USDA, 2010)

106–134

40.1 (boiled); 116.2 (microwaved) 71.7–62.2/2

115–116

∼90-∼135 (blanched); 112–117 (microwaved)

(Vanderslice et al., 1990) (Mangels et al., 1993) (Favell, 1998) (Howard et al., 1999)

84 (pillow packed)

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55–56 (florets blanched/frozen); 35–36 (stems blanched/frozen) 90 (boiled) 73 (boiled); 75 (high pressure boiled); 106 (steamed); 54.9 (microwaved) 18–21 35.2–83.5 (floret boiled); 36.0–100.0 (stem boiled); 35.5–85.1 (floret microwaved); 36.5–103 (leaves microwaved) 110–170 65–120 (stir fried) ∼60 (blanched); ∼25 (boiled)

∼20 (frozen) 62.7 (frozen); 373.2 (blanched/frozen) Brussels sprouts

74.1 ∼30-∼50 (frozen)

Cauliflower 66–73 ∼35 Chinese cabbage (Pak-choi) Chinese cabbage (Pe-tsai) Collards

Mustard cabbage (Indian mustard) Mustard spinach (tender greens) Red cabbage Savoy cabbage White cabbage Turnip tops

26.8

Turnip greens

4.4 20–30 (frozen); 25–35 (dried, blanched, frozen)

∼465-∼828∗

(Murcia et al., 2000) (Davey et al., 2000) (Vallejo et al., 2002a) (Franke et al., 2004) (Zhang and Hamauzu, 2004)

(L´opez-Berenguer et al., 2007) (Moreno et al., 2007b) (Sikora et al., 2008) (Patras et al., 2011)

(Davey et al., 2000) (Puupponen-Pimi¨a et al., 2003) (Sikora et al., 2008) (USDA, 2010)

14–15 15.8

(Franke et al., 2004) (USDA, 2010)

68–10 18.2 41 (boiled)

25.3

(Franke et al., 2004) (USDA, 2010) (Vanderslice et al., 1990) (USDA, 2010) (Davey et al., 2000) (Sikora et al., 2008) (Hagen et al., 2009) (USDA, 2010)

4.8 (boiled) 65.0

(Vanderslice et al., 1990) (USDA, 2010)

10.8 17.0 37.5 24.4 (boiled) 18.2 29.4 (steamed); 0 (boiled/high pressure boiled) 3.9

(USDA, 2010) (USDA, 2010) (USDA, 2010) (Vanderslice et al., 1990) (USDA, 2010) (Francisco et al., 2010)

62 ∼15 (boiling); ∼65 (blanching)

39.7 (steamed); 0 (boiled/high pressure boiled) NDB = USDA nutrient databank identifier. ∗ mg 100g−1 dw.

(Hussein et al., 2000) (Murcia et al., 2000)

40 (CMC coated); 52 (chitosan coated) 62.0 ∼15-∼40 (boiled); ∼35-∼80 (blanched) 55 14.4 (boiled); 73 (Blanched) ∼35 (blanching); ∼25 (boiled) 26.0

Curly Kale ∼45

Source (reference)

(Ansorena et al., 2011) (USDA, 2010) (Sikora et al., 2008)

(USDA, 2010) (Mondrag´on-Portocarrero et al., 2006) (Francisco et al., 2010)

BRASSICA FOODS AS A DIETARY SOURCE OF VITAMIN C

and temperature regimes

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